Process for the fermantation of tobacco



United States Patent Inventor Appl. No. Filed Patented Assignee Priority PROCESS FOR THE FERMENTATION 0F TOBACCO 5 Claims, 3 Drawing Figs.

US. Cl. 131/140, 13 1/135 Int. Cl. H A24b 03/02. A24b 03/12 Field of Search 131/17,

[56] References Cited UNlTED STATES PATENTS 1,671,259 5/1928 Schloesing 131/143 1,719,291 7/1929 Federman 131/143 1,927,180 9/1933 McConnell. 131/143X 802,487 10/1905 Wimmer..... 131/143 2,429,567 10/1947 Sowa 131/140 3,396,735 8/1968 Von Bethmanniet al. 131/143 Primary Examiner--Melvin D. Rein Attorney-Werner W. Kleeman ABSTRACT: Process for the fermentation. of tobacco wherein air is passed through the tobacco at least substantially uniformly. the air is recirculated after passage through the tobacco and during recirculation desired components are selectively removed from the recirculated air. Preferably. the tobacco is stacked in a plurality of layers of small height and the air is passed through each ofthe layers across the entire cross-sectional area thereof.

PATENTED on: emu 3545;455-

sum 2 or 2 ATTORNEYS PROCESS FOR THE FERMANTATION OF TOBACCO This application is a division of my earlier application Ser. No. 568,457 filed July 28, 1966 now U.S. Pat. No. 3,399,680.

The present invention pertains to an improved process for the fermentation of tobacco, by means of streaming air. The inventive process uses an apparatus of the type comprising a plurality of towerlike cells superimposed on top of one another to provide at least one column, each cell being laterally bounded by cell wall means and having a gas permeable partition member situated within each such cell for subdividing the latter into a charging compartment for the tobacco and a flow compartment for the air, the charging compartment of each such cell being arranged above its flow compartment.

Row tobacco is subjected to a previous treatment before it is processed into the actual smoking article, for instance, pipe tobacco, cigarettes of cigars. This treatment is quite different, depending upon theorigin of the tobacco itself and the smoking article to be produced. However, for most practical purposes it can be classified into three main treating techniques, namely, fermentation, mellowing and wetting or moistening.

During fermentation the tobacco must be brought to a certain moisture content and temperature in order to produce certain changes in the compounds contained in the tobacco. In the so-called stack or pile fermentation, primarily employed for cigar tobacco, the required heat or thermal energy is delivered by exothermic fermentation. Due to the cooling and drying at the marginal region of the stack, it is necessary to restack the tobacco a number of times. Such restacking requires a considerable expenditure of labor and also the uniformity of the thus obtained material leaves something to be desired. With chamber fermentation employed primarily for neutral tabaccos, especially cigarette tobacco, the tobacco units are washed with conditioned air in closed insulated compartments.

The adjustment and maintenance of certain moisture and temperature values of the tobacco is important. With some of the known prior art processes a gaseous and/or vapor containing medium is passed through the tobacco in order to mellow and wet it. However, these processes are not suitable for fermentation because it is not possible to economically permeate the large quantities of tobacco which are available and must be immediately processed after harvesting and drying. On the other hand, during moistening the tobacco collapses, bringing about irregular compression of the tobacco charge and resulting in irregular treatment. This compression is always greater in the lower tobacco layer due to the inherent weight of the tobacco than in the upper layer.

Most of the installations which were previously employed for the treatment of tobacco by means of gaseous medium operate with relatively high pressure because of the high flow resistance of the charge. As a result, they must be constructed with correspondingly strong and therefore expensive walls, require a great ventilation capacity and use a great amount of energy.

Accordingly, it is a primary object of the present invention to provide an improved process for the fermentation of tobacco, which overcomes the drawbacks of the prior art techniques. Another considerable object of this invention is directed to the provision of an improved process which renders it possible to conduct air substantially process through the tobacco.

Still a further significant object of this invention concerns the provision of an improved process for the fermentation of tobacco which with a minimum expenditure of time and under optimum conditions, with space requirements and mechanical work being held to a minimum because the tobacco from the time of introduction up to drying remains in the same apparatus.

A further object of the present invention is to provide an improved process for the fermentation which renders it possible to free the tobacco during the treatment with air from certain undesired volatile components, particularly alkali components, without removing to an undesirable degree desired tobacco components components, such as aroma components.

Yet a further object of this invention is to provide tobacco fermentation processes which enable utilization of the sensible heat of the tobacco developed during fermentation to be employed for the .most part for carrying out the fermentation operation itself.

An ancillary yet equally significant object of the present invention is directed to an improved process of the type described rendering possible an exact control of the different treating operations.

In order to achieve these and still further objects of the invention, which will become more readily apparent as the description proceeds, the inventive process is manifested by the features that the flow compartment of each cell of the ap paratus used thereby is provided with a conduit for the infeed or outfeed of the air, whereas cover means is provided for the uppermost cell and floor means for the lowermost cell of the column. Further, such cover means cooperate with the uppermost cell to provide therebetween an additional flow compartment, and a further conduit for the air communicates with such additional flow compartment.

Other features, objects and advantages of the invention will become apparent by reference to the following detailed description and drawings in which:

FIG. 1 schematically depicts a cross section of one cell of an apparatus used with the inventive treatment and provided with a floor and a cover portion;

FIG. 2 schematically depicts a column provided with floor and cover portion and assembled from a number of cells of the type shown in FIG. 1, further depicting infeed and outfeed conduits for the air; and a FIG. 3 schematically depicts the circuit diagram of an installation formed from a number of columns of the type shown in FIG. 2 and having two separate recirculation systems, each of which contains one circulation pump, an air-conditioning unit, at least one analysis device and one of them has a trap or separator.

Turning attention now to the drawings, it should be distinctly understood that only enough of the specific physical structure of the various embodiments of inventive process described herein have been shown to enable one skilled in the art to readily understand the underlying concepts of the invention. Specifically, by referring to FIG. 1 it will be noted that C embodies therein depicted cell or cabinet C embodies four cell sidewalls arranged relative to one another so as to provide a substantially square cross-sectional configuration for instance, two of such sidewalls ll, 12 being visible in cross section. These sidewalls ll, 12, etc. are connected at the top and bottom with a flat frame member 13 and 14 respectively. A thin layer of foam material 15 is secured to the upper frame member 13. In the exemplary embodiment, these sidewalls 11, 12, etc. are externally covered with a thick layer, as generally denoted by reference characters 16, 17, of suitable heat insulating material. On the other hand, such heat insulation can also be provided by having a double wall construction of the sidewalls, in which case then, appropriate heating elements or the like can be mounted between such sidewalls. This double wall construction can also be used for conducting the gaseous medium into the flow compartment 22 of the corresponding cell or cabinet C as will be more fully developed shortly.

At the lower region of the cell chamber D surrounded by the aforementioned sidewalls l1, 12, etc. there is mounted a perforated partition member 18, for instance formed of sheet metal, which is disposed in such a manner that this chamber D is divided into two unequal compartments. The portion or compartment of the chamber D arranged between the perforated partition member or sheet metal plate 18 and the upper frame member 13 serves to receive the tobacco, and hereinafter will be conveniently referred to as the filling or charging compartment 21. The portion or compartment of the A member 18 and the lower frame member 14 serves to facilitate the uniform thru throughflow of the gaseous medium, and hereinafter will be conveniently referred to as the flow compartment 22. One of these sidewalls of the flow compartment 22, such as sidewall 16, is provided with a hole or aperture 16a in which there is set a tube or pipe 19 equipped with a regulating and shutoff valve 20 of any suitable construction. By way of illustration, the depicted cell C is about 60 centimeters high and possesses a free internal cross section of about 1 square meter. The perforated sheet metal plate or partition member 18 is situated about centimeters above the lower frame member 14.

The floor 23 has the same cross-sectional configuration as the lower frame member 14 of the cell and is covered at its upper end with a suitable layer of foam material 24.

At the top the cell or cabinet C can be closed or obturated by a cover portion or member E. The latter incorporates a bearing surface 28 which fits onto the frame member 13 of the cell C, flat sidewalls 25 and an upper closure plate 26, all of which encompass an internal compartment 27. A tube or pipe 29 piercingly extends through one of the sidewalls, such as the one shown at the right of FIG. 1, and is provided with a suitable regulating and shutoff valve 30.

- FIG. 2 schematically depicts the manner in which a number of such cells or cabinets C can be stacked on top of one another to form a vertical column, generally designated by reference character F. It will be recognized that the lowermost cell 200 is placed upon the floor member 100 and the intermediate layer of foam material 124 ensures for a practically airtight connection between cell and floor. Above the cell 200 there is situated the cell 300, whereby the contacts surface between the upper frame member 200a of the lower cell and the lower frame member 300a of the upper cell 300 is sealed by the layer of foam material 215. In the depicted exemplary embodiment 6 cells or cabinets are stacked upon one another in the described manner, but obviously a greater or less number could be employed. Moreover, the laterally protruding conduits or pipes 219, 319, 419, 519, 619, 719 of each tube neighboring elevationally arranged cells always are directed in the opposite sense. Finally, the depicted column F is sealed at the top by the cover member 800, the conduit or pipe 829 of which is directed in the same manner as would be the conduit of a cell standing in its place. These cells are loosely stacked and only sealed by the layer of foam material provided at the upper frame members. The individual pipes or conduits are detachably connected with both of the stationary conduits 40 and 41, the conduit 40 serving for the infeed of the streaming gaseous medium and the conduit 41 for outfeed or delivery thereof.

The tobacco fermentation installation schematically depicted in FIG. 3 contains three columns, 50, 51 and 52, each of which consists of individually stacked cells C, just as was the case with the column F depicted in FIG. 2. The pipes or conduits 140, 240 and 340 correspond to the conduit 40 of FIG. 2 and the pipes or conduits 141, 241 and 341 to the conduit 41 thereof. As will be readily apparent by inspecting the schematic circuit diagram of the installation of FIG. 3, each aforementioned conduit thereof can be selectively connected, through the agency of associated control valves 142, 242, 342 and 143, 243, 343, to one of two different recirculation systems or cycles. To be able to better distinguish between these two recirculation systems, one of them is depicted in solid line and the other with dashed lines.

The recirculation system or cycle shown with solid or full lines contains a circulation pump 60 for the an air-conditioning installation 61, which can simultaneously be employed for the infeed or outfeed for moistening or drying and for heating or cooling of the air. At the output side of this air-conditioning plant or installation 61 there is connected an analyzer 65 which examines the air for properties important for the tobacco treatment. Moreover, a pressure line or conduit 62 leads from the output side of the analyzer 65, via the control valves 142, 242, 342 and the conduits 140, 240, 340, to the columns 50, 51, and 52. The return flow from the columns 50, 51 and 52 is conveyed through the conduits 141, 241 and 341 and control valves 143, 243 and 343 and a suction line 63 to an analyzing device 66 and from this location to the separator or absorption means 64 which is directly connected with the circulation pump 60.

The recirculation system depicted in dashed or broken lines in FIG. 3 likewise contains a circulation pump 70 for the air, the delivery capacity of which, however, is considerably greater than that of the circulation pump 60, and an air-conditioning installation or plant 71 which, like the conditioning plant 61, can be employed for the infeed or removal, moistening or drying, heating or cooling of the air. At the output side of this air-conditioning installation 71 there is arranged an analysis device 75, similar to the analysis device 65 previously considered. A pressure conduit 72 leads from the analysis device 75 to the control valves 142, 242 and 342 and, from this location, through the same pipes or conduits as previously considered, to the different columns 50, 51 and 52. Once again, the return flow from these columns takes place via the control valves 143, 243 and 343 and a suction conduit 73 directly to the circulation pump 70, in other words the circulation system with the greater delivery capacity does not possess any separator.

There will now be considered the mode of operation of the schematically depicted installation of FIG. 3 for the fermentation of tobacco. Initially, the charging compartment of a larger number of cells or cabinets C are filled with raw tobacco, thereafter the filled cells stacked into a column F, as shown for instance in FIG. 2, and this column is then connected to two recirculation systems as shown in FIG. 3. At first the recirculation system with the lower delivery capacity, at which there is mounted the separator 64, is switched in. Circulation pump 60 delivers air which is preheated in the air-conditioning plant or installation 61, through the pressure conduit 62 and the conduits 140, 240 and 340. The circulation of the hot air internally of the cells C of a column F is schematically represented in FIG. 2 by broken lines having applied thereto arrow heads.

More precisely, the warm air moves from the conduit 40 through the valves 220, 420, 620 and 830 into the respective flow compartments 222, 422, 622 and the hollow internal compartment of the cover portion 800. The warm air coming from the lowermost flow compartment 222 and the internal compartment 827 of the cover portion 800 only has the possibility of streaming through the neighboring charging compartment 221 and 721 respectively. The warm air arriving in the flow compartments 422, 622 streams through the neighboring charging compartments 321, 421 and 521, 621 respectively. The inlet valves are accordingly regulated such that through each of the valves 420 and 620 approximately twice as much warm air flows as through each of the valves 220 and 830. The hot air, after it has streamed through the charging compartments 221, 321 and 421, 521 and 621, 721, collects in the flow compartments 322, 522 and 722 respectively. From this location it moves through the outlet valves 320, 520 and 720 into the conduit 41, the latter of which is operatively connected with the suction conduit 61 of the recirculation system of FIG. 3.

The streaming warm air brings about fermentation of the tobacco located in the charging compartments. The beginning, the course and the end of fermentation can be monitored with the aid of the analysis or analyzer device 66 by controlling the air emanating from the columns 50, 51 and 52. In this respect, it is not necessary that fermentation take place in the streaming medium, rather such stream can be cut off after the beginning of fermentation and, only for the purpose of analysis switched in at greater time intervals, or else the quantity of the circulated medium can be strongly throttled. Separator 64 ensures that gaseous or vaporous compounds produced during fermentation, and which should not again be brought into contact with the tobacco, are selectively separated from the circulated medium.

As soon as fermentation can be considered to be complete,

. the composition of the warm air in the air-conditioning installation 61 is changed, a change which can be monitored by the analyzer device 65, and excess moisture is removed for such time from the circulating air until the tobacco located in the cells C has attained a predetermined moisture content.

It is to be clearly understoodthat the heretofore described installation according to the exemplary embodiments given herein can, of course, be modified in a number of different ways depending upon specific requirementsFor instance, the individual cells need not possess a square cross-sectional configuration, rather could equally well have a rectangular or circular one, or any other suitable shape. When assembling the cells into columns the position of the conduits or pipes protruding from the cells is dependent upon the location in which the main conduit lines are disposed, that is to say, the conduits of the stacked cells could for instance also all be directed in the same direction or sense. If it is thought advisable or necessary, then an analyzer or a pressure or temperature measuring device could be mounted at the pipe or conduit of each individual cell, whereby the individual stages of .the fermentation for relatively small quantities of tobacco can be individually controlled. Moreover, a treatment installation such as depicted in FIG. 3 can incorporate less than or more than three columns, depending upon the capacity of the recirculation system, the number of cells in each column and the time required for fermentation. Furthermore, insofar as the individual columns are concerned it is completely irrelevant whether the direction of flow of the air is as shown by the arrows in FIG. 2 or in the opposite direction thereof. The flow direction is determined by the external recirculation system.

Naturally, it is sufficient if only one recirculation system is provided for the entire installationand such can be open, partially closed or completely closed. The use of a number of recirculation systems is particularly advantageous if a number of columns can be connected and there is desired a working operation which is as continuous as possible. Then, while one column is being charged with tobacco, at the same time fermentation takes place in another column and so forth.

With the method practiced according to the teachings of the present invention, the tobacco is preferably distributed in a number of superimposed layers of small height, wherein the individual layers preferably arranged at a distance from one another and are passed or permeated throughout their entire width practically uniformly by the air. The stage for the selective removal or separation of componentsof the recirculating medium, which either emanate from a previous treatment or from the tobacco itself and as a general rule are alkali reacting volatile components, such as ammonia, nicotine, pyridine and the like, can constitute a conventional absorber for instance. There the air is treated with an acidic washing medium such as aqueous sulfuric acid. Advantageously, the recirculating stream of air is conditioned, that is, is regulated to a certain temperature and moisture content. The use of sulphuric acid as absorption agent is preferred, because this acid also renders possible the adjustment of a desired atmospheric moisture in the air. The absorption stage can also be used to advantage for removing the carbon dioxide formed primarily during fermentation, and indeed, independent of the removal of alkali components or together with such. In such case, the absorber is preferably charged with an aqueous potassium hydroxide solution.

The fermentation process can be controlled by continuously measuring the value of the pH in the recirculation system, the content of ammonia, C0 nicotine and the like.

The invention will be further better understood by referring to the following Example:

EXAMPLE In order to carry out tobacco fermentation it is possible to operate in the following manner: Dried tobacco bushels or loose tobacco leaves, in a layer height of about 40 to 60 centimeters thickness, are placed into the individual cells of a column of the type depicted in FIG. 2, whereby free air passages are prevented by appropriate packing. The moisture content of the tobacco amounts to about 17 percent to 22 percent, the specific value being dependent upon the climate. The charging density amounts to about 200 to 250 kilograms per cubic meter. After connecting the conduits 40, 41 (FIG. 2) or 140, 240, 340 and 141, 241 and 341 (FIG. 3) heating is initiated. In this respect, the air delivered through the conduit 62 for instance, under the action of the ventilator or pump 60 is heated in the air-conditioning installation 61. If the tobacco contains a larger portion of green material, one starts with an approximately percent to percent relative humidity of the air by approximately 80 percent to 90 percent relative humidity of the air by appropriate introduction of water or vapor -to the air-conditioning installation 61. The temperature of the recirculating air is regulated to 40 C. to 50 C. After about 24 hours the temperature of the recirculating air is increased to 55 C. to 65 C. and the moisture content of the tobacco is brought to 18 to 23 percent. As already developed, in order to prevent thermal losses in the columns such are advantageously provided with insulating walls or with a double wall construc' tion through which the recirculating gaseous medium flows. In this manner it is possible to prevent condensation of moisture in the walls of the columns.

As soon as the air flowing out of the tobacco exhibits an alkali or base reaction, the absorption function of the separator or absorber 64 is brought into operation, for instance by charging such apparatus 64 with sulphuric acid until the air is practically neutral. This can be carried out most simply by shutting off the water supply for the air-conditioning installation, whereby, if necessary, the absorption stage can be called upon for drying the recirculating gas. Naturally, removal of water can also take place directly in theyair-conditioning installation 61, for instance through condensation. Thereafter, the tobacco is brought to a moisture content of 14 to 17 percent and at the same time cooled to 25 C. to 40 C., by recirculation of water vapor-containing air through the installation. Also this treatment step can be quickly and simply carried out by appropriate control of the delivery capacity and operation of the air-conditioning unit or installation. Thereafter, the tobacco is removed from the cells of the column or columns and pressed.

While there is shown and described present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. Process for the fermentation of tobacco, comprising (a) stacking the tobacco in a plurality of layers of small height on perforated support means which are within a chamber having heat insulating walls, (b) recycling conditioned air through each of said layers across the entire cross-sectional area of each of said layers to heat and moisten the tobacco substantially uniformly to a temperature and moisture necessary for the fermentative degradation of the constituents of the tobacco, (c) stopping the recirculating of said air and maintaining the temperature of the tobacco by utilizing the heat of the fermentation process which is retained by means of the heat insulating walls and switching in the stream of recirculating air intermittently and selectively absorbing and thereby removing products of decomposition of the tobacco when undesirably large amounts of said decomposition products have accumulated in the air surrounding the tobacco and (d) after completion of the fermentation, drying the tobacco to a desired moisture content by passing air through the tobacco.

2. A process according to claim 1 which includes the step of passing air through each of said layers from opposed sides thereof.

3. A process according to claim I, which further comprises placing said tobacco adjacent to the walls of said chamber.

5. A process according to claim 1 wherein an alkali reacting liquid is employed for the selective removal of carbon dioxide from the air. 

